Closure for retort container

ABSTRACT

A retortable container is formed with an opening formed defined by a projecting rim. The rim includes an external surface and securing structure formed thereon. A flexible membrane is sealed to the rim and closes the opening. A closure is provided having a molded plastic tubular ring and a separately formed molded plastic disk. The tubular ring includes an overlapping flange at a top and directed inwardly towards an inwardly positioned open area. The skirt includes an engagement structure for securing the closure to the external surface of the rim. The disk is separately attached to the ring within the open area after the retort process is applied to the sealed bottle.

FIELD OF THE INVENTION

The present disclosure relates to containers for products, and moreparticularly relates to retort containers for food.

BACKGROUND

Retort containers are hermetically sealed after filling with a foodproduct, and are then heated to a temperature of at least about 220° F.for a period of time to ensure that all microorganisms in the containerhave been killed. Cycle times for heating or cooking the containercontents typically exceed 10 minutes. As the temperature rises, thepressure inside the container also increases. An overpressure controlsystem is often used to reduce the pressure differential between theinside and outside of the container. As such, the pressure differentialtypically does not exceed 5 pounds per square inch (psi). After heating,retort containers typically do not require refrigeration prior toopening and consuming the contents. Retort containers can be stored forextended periods in their sealed condition.

For many years, metal cans were the predominant type of retortcontainers. Plastic retort containers have been developed. In plasticretort containers, the container lid must be hermetically sealed to thecontainer with sufficient strength to withstand the elevated temperatureand pressure conditions during the retort operation. However, the sealstrength must be limited so that the consumer may readily remove the lidand seal. Other requirements for all-plastic retort containers and lidsinclude high-barrier performance against water vapor and oxygen, andfast sealing speed.

An all-plastic retort container having a sealing membrane that isadhesively sealed to the container (as opposed to being heat-sealed tothe container) is disclosed in Nomula US 2005/0255266 A1.

A high-barrier plastic closure for a retort container is disclosed inNomula U.S. Pat. No. 7,364,779 and Williams et al. US2005/0145630 A1.

A composite closure for a retort container is disclosed in German et al.U.S. Pat. No. 6,276,543. The closure includes a metal disk for coveringthe container opening. The disk is retained by an outer band that isthreaded onto the rim of the container.

SUMMARY

In one aspect of the disclosure, a retortable container is provided, forexample a bottle, for storing product. A reservoir is defined within thecontainer and an opening is provided for discharge of the product. Theopening is formed within an upstanding rim projected from the reservoirbody. The rim includes an external surface and may further includesecuring means thereon. A membrane is directly secured to the rim,closing the opening and sealing the reservoir contents. The membrane ispreferably formed from a flexible material and seals the product withinthe reservoir. A closure is provided in the form of a tubular ring and aseparately formed disk. The tubular ring includes a skirt formed about acentral axis and an overlap flange portion at a top end of the skirt.The flange is directed inwardly towards the central axis. An open areais provided radially inward of the flange. Engagement means may beprovided on an inside wall of the skirt for engaging the rim securingmeans. The separate disk structure is provided and conforms to thedimensions of the open area. The disc is attached to the ring, closingthe open area, after the retort process.

In a further aspect of the retortable container the securing means onthe container rim and the engagement means on the skirt may be formed asmatching threads for coupling the closure to the container rim.

In a further aspect of the retortable container the rim may include asealing surface and an adhesive seal is provided for fixing the membraneto the sealing surface, hermetically sealing the product within thereservoir. The overlap flange of the tubular ring preferably engages themembrane at the sealing surface in the closed position of the ring onthe rim of the container.

Other features of the present invention will become apparent from thedetailed description to follow, taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there is shown in thedrawings a form which is presently preferred; it being understood thatthe invention is not limited to the precise arrangements andinstrumentalities shown.

FIG. 1 is an exploded perspective view of an embodiment of a containerand closure as contemplated by the present disclosure.

FIG. 2 is a partially assembled perspective view of the container andclosure embodiment of FIG. 1.

FIG. 3 is a partial cross sectional view of the container and closureembodiment as shown in FIG. 2.

FIG. 4 is a cross sectional view of the container and closure embodimentgraphically showing the retort process.

FIG. 5 is a partial cross sectional view of the fully assembledcontainer and closure embodiment according to FIG. 1.

FIG. 6 is a partial cross sectional view of the container showingremoval of the sealing membrane portion of the closure.

FIG. 7 is a re-assembled container and closure, after removal of thesealing membrane.

DETAILED DESCRIPTION

Referring now to the drawings, where like numerals identify likeelements, there is shown in FIG. 1 a retortable container construction,which is generally referred to by the numeral 10. The container 10includes a bottle 12 defining a reservoir therein, a sealing membrane14, a closure ring 16 and a sealing disk 18. The bottle 12 includes areservoir body 20 and a projecting neck 22. A discharge opening 24 isdefined by the neck portion 22 of the bottle 12. A rim 26 is formed onthe top end of the neck 22 and surrounds the opening 24. The rim 26includes a sealing surface 28 for securing the membrane 14 to the rim 26and closing the opening 24. As shown, the elements of the container 10are axially positioned around a central axis line 30.

In the intermediate assembly shown in FIG. 2, as also shown in crosssection in FIG. 3, the membrane 14 is sealed to the sealing surface 28of the rim 26. The closure ring 16 is secured to the projecting neck 22of the bottle 12. The separate disk 18 is not attached to the ring 16.As shown, the ring 16 is formed from a tubular body 32 and an inwardlydirected flange 34. The inner rim of the flange 34 defines a diskengagement surface. The flange 34 defines an opening in the closure 18,with the open area 38 overlapping the bottle opening 24, with themembrane 14 positioned there between. As more particularly shown in thecross section of FIG. 3, a seal 40 is provided between the membrane 14and the sealing surface 28 of the rim 26 of the bottle 12. An adhesive42 may be provided between the upper surface of the membrane 14 and thelower surface of the flange 34. Engagement means 44 is provided on theinside wall of the closure ring 16, preferably in the form of a threadedsurface. A corresponding securing means 46, again preferred to be athreaded surface, is provided on the outside wall of the neck 22 of thebottle 12.

In FIG. 4, there is graphically shown the retort cooking process for theintermediate assembly (FIGS. 2 and 3) of the container 10. Product (notshown) is stored in the reservoir body of the bottle 12 and sealed bythe membrane 14. The ring 16 is attached to the neck 22 of the bottle 12and the inwardly projecting flange 34 overlaps the sealing surface 28and engages the outer periphery of the membrane 14 as sealed to thesealing surface 28. The sealed bottle 12 is then subjected to anexternal heating source 48, which may include microwave energy. Theapplied heat/energy 48 creates heat and pressure 50 within the sealedbottle 12. As shown, the heat/energy 48 is also applied through themembrane 14 covering the open area 38 defined inwardly of the flange 34on the closure ring 16.

In FIG. 5, there is shown in cross section the final assembly of thecontainer 10. The sealing disk 18 is positioned within the open area 24as defined by the ring 16 and inwardly directed flange 34. As shown, theflange 34 and body of the ring 16 form a stepped surface 52. The disk 18preferably includes a similarly stepped surface 54 on its outerperiphery. The disk 18 and corresponding surfaces 52, 54 serve tocooperate with one another to retain the disk 18 within the (previously)open area defined by the ring 18. The disk 18 is inserted into theoutwardly open area 24 from above the ring 16 and completes the closureformed by the ring 18. The disk 18 is externally inserted and snaps intothe opening 38. The preferred engagement between the disk 18 and ring 16is an interference or friction fit. The dimension tolerances arecontemplated to be relatively close, providing a liquid tight seal. Thestepped surfaces 36 assist in forming the seal. An adhesive or similarmaterial may be utilized. Other forms of attachment of the plastic diskto the plastic ring may also be used.

In FIG. 6, there is shown the removal of the membrane 14 to provideaccess to the product stored within the reservoir 20 of the bottle 12.As illustrated, the membrane 14 is provided with a gripping tab 56 thatmay be partially separated from the body of the membrane 14 creating ameans for separating the membrane 14 from the sealing surface 28 of therim 26 of the bottle 12. The gripping tab 56 is exposed by removal ofthe ring 16 and disk 18 combination (as shown in FIG. 5) from the neck22 of the bottle 12. The threads or similar means (44, 46) permit theclosure to be easily removed from the bottle. Once the membrane 14 isremoved, the discharge opening of the bottle 12 is open for discharge ofthe product.

The resealing of the bottle 12 is shown in FIG. 7 by the attachment ofthe closure ring and disk combination 16, 18 to the neck 22 of thebottle 12. The threads 44, 46 (or similar structures) secure the ring 16and its attached disk 18 to the bottle 12, after removal of the membrane14. Hence, the product within the reservoir 20 may be partiallydispensed after removal of the membrane 14 (FIG. 6) and the bottle 12resealed by the combination ring 16 and disk 18. It is preferred thatthe ring 16 be dimensionally formed, such that the flange 34 engages thesealing surface 28 of the rim 26 when the ring 16 returns to seal thereservoir opening 24.

The container 10 is assembled prior the retort process (FIG. 4) withoutthe disk 18, as shown in FIGS. 2 and 3. The adhesive 42 is provided onthe upper surface of the membrane 14 or on the bottom surface of theflange 34. This adhesive 44 serves to retain the membrane 14 inposition, during application of the ring 16 onto the neck 22 of thebottle 20. Hence, the membrane 14 is secured to the underside of theflange 34 within the ring 16 by the adhesive 42. Upon attachment of thering 16, the membrane 14 extends across the open area 38. Thecombination ring 16 and membrane 14 is then applied to the neck 22 ofthe bottle 20

In the present constructions, the ring 16 is contemplated to be made ofa plastic material as formed by an injection molding process. The diskportion 18 of the completed closure is contemplated to also be formed byinjection molding. The disk 18 is preferably made of the same materialas the ring 16, but may be any compatible material. The preferredmaterial is polypropylene. The closure parts—disk and ring—arepreferably made of a single material or monolayer. The disk 18 may beretained within the outwardly open area 38 of the ring 16 by africtional engagement between the stepped surface 36 of the ring 16 andengagement surface 54 of the disk 18. An adhesive is preferably alsoprovided. Other securing means may be used, such as ultrasonic welding,spin welding, etc.

The membrane 14 may be made of any number of materials. The membrane maybe formed from a metal foil patch, forming the barrier layer. Apolypropylene sealant layer may be provided on the lower surface of thefoil. The polypropylene will serve as a sealant layer and deterfracturing of the foil. A tie layer may be provided between the foil andthe polypropylene and an exterior coating may be applied to thepolypropylene (or directly to the foil) for forming a fracture layer. Apolyester material may be added to the top surface of the foil. Thecombination of polyester, foil and polypropylene may be formed as alaminate or otherwise. Alternatively, the foil material may be coated onthe top with a lacquer or similar material. An organic coating may beapplied to the bottom surface of the foil for forming the sealingmaterial for the membrane to the rim surface 28. Other materialcombinations are possible, beyond these preferred structures.

The membrane is contemplated to be sealed to the sealing surface 28 ofthe container rim 26 after application of the ring 16 to the rim 26.Generally, the seal is created by an induction heating process.Induction heating or sealing is a non-contact method of heating ametallic material and attaching it to the top of a plastic (or glass)container. The sealing process takes place after the container has beenfilled and capped. The combination ring 16 and membrane 14 is positionedon the rim 26 before the application of energy. The combination is thenpassed under an induction coil, which emits an oscillatingelectromagnetic field. The conductive foil layer begins to heat in thepresence of the electromagnetic energy. However, the plastic ring 16 andthe container rim 26 are not affected by the energy exposure. The heatfrom the foil serves to melt the sealing layer on the bottom of thefoil, and the polymer sealing material flows onto the rim 26. Whencooled, the sealing layer or coating creates a bond with the sealingsurface 28 of the container rim 26, resulting in a hermetic seal.Neither the container nor its contents are affected. The cycle time forthe energy application is a matter of seconds. The engagement of thering 16, including the contact of the flange 34 with the portion of themembrane 14 overlapping the rim surface 28, serves to fix the positionof the membrane 14 and secure the final seal with the rim 26. The flangeengagement is contemplated to support the membrane 14 during retortheating. The resulting pressure differential may cause the membrane tobow outwardly. The bowing angle could potentially serve to create apealing action at the sealing surface 28. The flange 34 may be formedsuch that the position of the bowed surface is inward of the sealingsurface 28. The flange engagement of the membrane edge further securesthe seal during retort.

As an alternative to the induction sealing process, a sealing adhesivemay be provided on the sealing surface 28 of the bottle rim 26 orpattern applied on the underside of the membrane 14. Regardless of theform, the seal 40 is contemplated to have strength sufficient towithstand the heat and pressure of the retort process. The engagement ofthe flange 34 with the perimeter of the membrane 14, by means ofsecuring the ring 16 on the bottle 20, assists in maintaining the sealduring retort and thereafter. Further, a fracture layer is preferablyprovided. As such, removal of the membrane 14 from the sealing surface28 results in a physical break or tear of the layer, leaving a portionon the sealing surface. This construction simplifies the opening processduring removal of the membrane. Other forms of and materials for sealingmay also be utilized.

The ring 16 may be removed from the bottle 20, with the membrane 14remaining sealed to surface 28 on the ring 26 of the bottle 20. Themembrane seal 40 is maintained until the membrane is physically peeledfrom the rim 22 of the bottle 20, such as by use of the gripping tab 56(FIG. 6). The use of the gripping tab 56 creates a peeling forcesufficient for removal of the membrane 14 from the sealing surface 28 ofthe bottle rim 26.

Because the ring 16 includes an open area 38, the membrane 14 is exposedduring the retort process. Hence, heat transfer is not retarded by aclosed cap surface. Further, the sealing of the bottle 20 is created bya membrane material 14, rather than a rigid metal disk—which maybe madeof coated steel—as often utilized in some retort bottle typeapplications. Metal disks create a complication with respect torecycling operations, creating operational and mechanical issues duringa grinding or similar destructive process.

Additional structures and elements may be added to the ring and diskcombination, which forms the completed closure. For example, a tamperevident band may be provided at the base of the ring. One form of such aband includes ratchets that restrict opening of the closure, until theband is separated from the ring or otherwise deformed. Deformation ofthe bad provides an indication of prior use or tampering with theproduct within the bottle. Other tamper evident structures are known andmay be utilized. Various structures may be molded into the insidesurfaces of the ring and the perimeter of the disk. The form of the diskmay also vary, for example a change in color or graphics, to permit theuse of a generic ring structure within multiple product applications.Other modifications may be made to accommodate marketability needs anddesires.

The present disclosure shows and describes one or more exemplaryembodiments. It should be understood by those skilled in the art fromthe foregoing that various other changes, omissions and additions may bemade therein, without departing from the spirit and scope of thecontemplated invention, with the scope of the invention being defined bythe foregoing claims. Further, the terms herein are used in a genericand descriptive sense and are not necessarily for purposes oflimitation. The scope of the invention is set forth in the followingclaims.

What is claimed is:
 1. A method of forming of a retort container andclosure, comprising the steps of: providing a container having aninternal reservoir, the container having a defined opening for dischargeof product retained within the reservoir, the opening formed within anupstanding rim projected from a reservoir body, the rim having anexternal surface, filling a retortable product within the reservoir ofthe container, securing a sealing membrane to the rim of the containerafter filling the retortable product within the reservoir, the sealingmembrane closing the opening and sealing the retortable product withinthe reservoir; engaging a closure to the external surface of thecontainer rim and over the sealing membrane secured to the rim, theclosure formed by a tubular ring, the ring having an annular skirtformed about a central axis, an overlap flange portion at a top end ofthe skirt directed inwardly from the skirt towards the central axis, anopen area radially inward of the flange and engagement means on aninside wall of the skirt for engaging the rim external surface, the openarea inward of the flange exposing the sealing membrane, heating theretortable product within the sealed reservoir, including directing heatthrough the open area inward of the flange of the closure and throughthe exposed portion of the sealing membrane, and after the retortheating of the product within the sealed container, securing a disk tothe closure within and closing the open area inward of the flange on theclosure, the disk covering the previously exposed portion of the sealingmembrane.
 2. A method as if claim 1 wherein the container rim comprisesa sealing surface and further comprising the step of adhesively sealingthe membrane to the sealing surface for hermetically sealing theretortable product within the internal reservoir.
 3. A method as inclaim 2 wherein the flange of the tubular ring engages the sealingmembrane to retain the sealing membrane secured to the sealing surfaceon the rim of the container.
 4. A method as in claim 1 wherein the ringand the disk are each molded from a plastic material.
 5. A method as inclaim 4 wherein the plastic material is polypropylene.
 6. A method as inclaim 4 wherein the membrane comprises a foil material as a barrierlayer.
 7. A method as in claim 1, wherein a portion of the diskoverlapping the flange and an adhesive securing the disk to theoverlapped portion of the flange.
 8. A method in claim 1, wherein theflange includes a stepped internal surface and the disk includes amating peripheral surface, and wherein at least a portion of the matingsurface of the disk overlaps a portion of the stepped internal surfaceof the flange.